The present invention is directed to improvements to pumps, and in particular, pumps having flexible or resilient vanes extending from a rotor for engaging a rotor sleeve as the rotor rotates within the sleeve during operation of the pump.
Known flexible vane pumps exhibit several disadvantages. Among other things, operation of the known devices requires a relatively large input power supply thereby rendering the known devices energy inefficient. Additionally, the arrangement and components of the rotor assembly, and in particular, the flexible vanes of the known devices are subject to wear thereby limiting the useful operating life of the rotor and requiring replacement at a relatively frequent interval.
It is the primary object of the present invention to overcome the disadvantages of the known devices. In accordance with the preferred embodiments of the present invention, a pump is provided which is energy efficient and which has a useful life greater than that of the known flexible vane pumps. Other advantages of the pump will become apparent from the following description thereof, in conjunction with the drawings.
A flexible vane pump includes a rotor having a central axis and a plurality of flexible or resilient vanes extending radially outwardly from the rotor. The rotor is mounted for rotation within a cylindrical sleeve, and the ends of the flexible vanes engage the inner surface of the sleeve as the rotor rotates. A plurality of compartments are defined between pairs of adjacent flexible vanes, and the central axis of the rotor is offset relative to the central axis of the sleeve so that the volume of the compartments defined between adjacent flexible vanes varies as the rotor rotates within the sleeve. A plurality of fixed vanes also extend outwardly from the rotor and are arranged so that at least one fixed vane extends into each compartment defined between each pair of adjacent flexible vanes. The remote end of each fixed vane terminates before it engages against the inner surface of the sleeve to avoid contact with the sleeve as the rotor rotates. The fixed vanes provide structural support for the ends of the flexible vanes proximate to the central axis of the rotor and also enhance the flow of incoming fluid into the compartments defined between adjacent flexible vanes.
Inlet means for supplying fluid to the rotor assembly are coupled to an inlet end of the rotor sleeve such that incoming fluid flows along a plane which is substantially perpendicular to the plane of rotation of the rotor. In this manner, the compartments defined between the adjacent flexible vanes are quickly and efficiently filled with the incoming fluid. The rotor axis is outwardly tapered in a direction away from the inlet end, and this arrangement also enhances the efficient filling of the compartments with incoming fluid while expending relatively less energy to do so. The fixed vanes extending from the rotor further enhance the quick and efficient loading of the compartment with fluid by propelling incoming fluid rearwardly into each respective compartment so that subsequent incoming fluid is met with less resistance. The fluid inlet means coupled to the inlet end of the rotor sleeve include an inlet slot which permits incoming fluid to be received only at a predetermined area of the rotor sleeve at which the compartments defined between adjacent flexible vanes are contracted into their smallest volume. As the rotor rotates in the sleeve, the rotor compartment expands in volume to thereby create a partial vacuum causing additional fluid to be drawn into the compartment as the compartment continues to rotate across the inlet slot in the fluid inlet means. As each compartment passes the end of the inlet slot, it becomes sealed and begins to contract in volume, as a result of the offset orientation between the rotor axis and the sleeve, as the sealed compartment rotates towards an outlet means. The inner surface of the sleeve defines at least one slot in communication with the outlet means which is oriented tangentially to the direction of rotation of the rotor. The interaction between the contracted sealed compartment, the discharge slot defined in the inner surface of the sleeve, and the tangential outlet opening in communication with the slot, results in the efficient discharge of fluid from the compressed sealed compartment as it rotates across the tangential discharge means. The compartment now continues to rotate in a direction towards the inlet means where it is again filled with incoming fluid and the cycle repeats. The structural arrangement and cooperation of structure of the rotor, the sleeve, and the inlet and outlet means results in efficient loading and unloading of fluid, thereby decreasing the energy required to operate the pump.
In a further aspect of the invention, the sleeve received in the rotor housing has a greater width than the width of the rotor housing. Preferably, the sleeve is formed from metal, and the rotor housing is formed from plastic. By providing the metallic sleeve with a width greater than that of the plastic rotor housing, the sleeve will overcome and compensate for any deformities or variations in the dimension of the plastic rotor housing which might occur during fabrication of the plastic housing by molding operations.
Removable annular retaining rings on one or both lateral sides of the rotor permit individual vanes to be removed from the rotor for inspection, repair, or replacement. In this manner, individual vanes can be removed and replaced without replacing the entire rotor.
The annular retaining rings can be dimensioned to provide a space between the lateral sides of the rotor and side plates of the rotor housing. In this manner, direct contact between the lateral sides of the vanes of the rotor and the side plates of the rotor housing is avoided.
In a further aspect of the invention, the flexible vanes of the rotor are formed from separate components joined together which include at least two leaf springs and at least one laminate surface separating the leaf springs. Each vane also has a shoe element joined to the leaf springs and the laminate and oriented so that the outer surface of the remote end of the shoe engages the inner surface of the rotor sleeve when the rotor rotates within the sleeve. The use of flexible vanes comprising a plurality of leaf springs, preferably of different lengths, joined together and separated by a layer of laminate, reduces stress and wear that would otherwise occur if each vane were formed from a single thicker spring. Accordingly, the flexible vanes in accordance with the present invention extend the useful operating life of the rotor, and reduce the frequency of rotor replacement.
In a further aspect of the invention, the tip of the outer laminate layer forming the vane is folded over the next inner spring to assure that there is no direct contact between the metallic spring and the inner surface of the metallic rotor sleeve when the rotor rotates within the sleeve. In this manner, metal to metal contact is avoided, thereby increasing the efficiency of the pump and reducing wear on the metallic components.
The cooperating structure and arrangement of components of the device in accordance with the present invention results in a flexible vane pump which requires less energy to operate than comparable conventional pumps, and which has a useful operating life exceeding that of conventional pumps.